Clean Microsoft WSUS Content Folder

1) Correct any settings above or disapprove any approved updates.

2) Close any open WSUS consoles.

3) Go to Administrative Tools – Services and STOP the Update Services service.

4) In Windows Explorer browse to the WSUSContent folder (typically D:\WSUS\WSUSContent or C:\WSUS\WSUSContent)

5) Delete ALL the files and folders in the WSUSContent folder.

6) Go to Administrative Tools – Services and START the Update Services service.

7) Open a command prompt and navigate to the folder: C:\Program Files\Update Services\Tools.

8) Run the command WSUSUtil.exe RESET

Refference: http://blogs.technet.com/b/gborger/archive/2009/02/27/what-to-do-when-your-wsuscontent-folder-grows-too-large.aspx